7  Allelopathy Experimental Design

7.1 Make an observation

You will have made the observation that one of more parts of certain types of plants emit very distinct odors1.

  • 1 We would describe them as odoriferous.

    • Give it a try

    Brainstorm specific examples of plants and specific plant parts other than flowers that are odoriferous.

    Plant parts that are odoriferous could include leaves, fruits, bark etc - what are specific plants that stick out to you that are odoriferous?

    The fact that you can smell something suggest that they are releasing chemical compounds.

    7.2 Formulate a hypothesis and predict your expected outcome.

    Give it a try

    Brainstorm 2-3 hypothesis that could explain why plants may be releasing volatile chemical compounds and predict what you would expect to observe if your hypothesis is correct.

    Based on the information in our introduction, one hypothesis could be that these volatile chemical compounds are phytotoxic and the plant emit them as a form of interference competition.

    7.3 Design an experiment

    Specifically you will be designing a bioassay2 to test the allelopathic effects on radish seeds. Bioassays typically have a simple, easily repeatable design as you want to be able to assess your results within a few weeks.

  • 2 A bioassay is an experiment designed to determine the properties and effects of a drug or chemical on the bodies of living organisms by testing it under controlled laboratory conditions.

    • We will be using radish seeds to test effects, their seeds have sufficient nutrients to allow them to grow on their own without photosynthesizing for at least a week. We will be placing our bioassays in a cool, dark area to grow.

    Make sure you take a look at the materials that are available to you and consider how you might incorporate them into your design. Be as specific as possible to describe how you will run your experiment. Make sure you are taking detailed notes on your design in the GoogleDoc provided to you and be ready to discuss why you have made specific choices.

    Finalize your design after a discussion on key concepts on experimental design. Make sure you complete the experimental design cheat sheet and submit it on Canvas.

    7.4 Homework

    Complete the posted discussion questions and submit them on Canvas.